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Welcome to the Cbc home page

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Introduced new secondaryStatus 8 to indicate that solving stopped due to an iteration limit.

Solution pool is now accessible via the command line and the CbcMain* interface.

New mipstart option to read an initial feasible solution from a file.
Only values for discrete variables need to be provided.

Added Proximity Search heuristic by Fischetti and Monaci (off by default):
The simplest way to switch it on using stand-alone version is "-proximity on".
Proximity Search is the new "No-Neighborhood Search" 0-1 MIP refinement heuristic recently proposed by
Fischetti and Monaci (2012). The idea is to define a sub-MIP without additional constraints but with a
modified objective function intended to attract the search in the proximity of the incumbent. The approach
works well for 0-1 MIPs whose solution landscape is not too irregular (meaning the there is reasonable
probability of finding an improved solution by flipping a small number of binary variables), in particular
when it is applied to the first heuristic solutions found at the root node.

An implementation of Zero-Half-Cuts by Alberto Caprara is now available.
By default, these cuts are off. To use add to your command line -zerohalfCuts root (or other options) or just -zero.
So far, they may help only on a small subset of problems and may need some tuning.
The implementation of these cuts is described in
G. Andreello, A. Caprara, and M. Fischetti
"Embedding Cuts in a Branch and Cut Framework: a Computational Study with {0,1/2}-Cuts"
INFORMS Journal on Computing 19(2), 229-238, 2007​http://dx.doi.org/10.1287/ijoc.1050.0162

An alternative implementation of a reduce and split cut generator by Giacomo Nannicini is now available.
By default, these cuts are off. To use add to your command line -reduce2AndSplitCuts root (or other options).
The implementation of these cuts is described in
G. Cornuejols and G. Nannicini
"Practical strategies for generating rank-1 split cuts in mixed-integer linear programming"
Mathematical Programming Computation 3(4), 281-318, 2011​http://dx.doi.org/10.1007/s12532-011-0028-6

An alternative robust implementation of a Gomory cut generator by Giacomo Nannicini is now available.
By default, these cuts are off. To use add to your command line -GMI root (or other options).
The implementation of these cuts is described in
G. Cornuejols, F. Margot, and G. Nannicini
"On the safety of Gomory cut generators"​http://faculty.sutd.edu.sg/~nannicini/index.php?page=publications

To encourage the use of some of the more exotic/expensive cut generators a parameter -slowcutpasses has been added.
The idea is that the code does these cuts just a few times - less than the more usual cuts. The default is 10.
The cut generators identified by "may be slow" at present are just Lift and project and ReduceAndSplit (both versions).

Allow initialization of random seed by user. Pseudo-random numbers are used in Cbc and Clp. In Clp they
are used to break ties in degenerate problems, while in Cbc heuristics such as the Feasibility Pump use them
to decide whether to round up or down. So if a different pseudo-random seed is given to Clp then you may get
a different continuous optimum and so different cuts and heuristic solutions. This can be switched on by
setting randomSeed for Clp and/or randomCbcSeed for Cbc. The special value of 0 tells code to use time of day
for initial seed.

Building on this idea, Andrea Lodi, Matteo Fischetti, Michele Monaci, Domenico Salvagnin, Yuji Shinano, and Andrea Tramontani
suggest that this idea be improved by running at the root node with multiple copies of solver, each
with its own different seed and then passing in the solutions and cuts so that the main solver has a richer
set of solutions and possibly stronger cuts. This is switched on by setting -multipleRootPasses. These can also
be done in parallel.

Few changes to presolve for special variables and badly scaled problems (in CoinUtils).

New option -extraVariables <number> which switches on a trivial re-formulation that introduces extra integer variables
to group together variables with same cost.

For some problems, cut generators and general branching work better if the problem would be infeasible if the cost is too high.
If the new option -constraintFromCutoff is set, the objective function is added as a constraint which rhs is set to the current
cutoff value (objective value of best known solution).

Fix to report interruption on user event if SIGINT is received by CbcSolver.model->status() should now be 5 if this event happened.
Added method CbcModel::sayEventHappened() to make cbc stop due to an 'user event'.

You can obtain the Cbc source code either via subversion or in form of nightly generated tarballs. The recommended method is to use subversion because it makes it easier to obtain updates. The following commands may be used to obtain and build Cbc from the source code using subversion:

Doxygen Documentation

If you have Doxygen available, you can build the html documentation by typing

make doxydoc

in the directory
coin-Cbc. Then open the file coin-Cbc/doxydoc/html/index.html with a browser.
Note that this creates the documentation for the Cbc
package. If you
prefer to generate the documentation only for a subset
of these projects, you can edit the file coin-Cbc/doxydoc/doxygen.conf to exclude directories
(using the EXCLUDE variable, for example).

If Doxygen is not available, you can use the link to the Cbc html documentation listed below.